Many different structures span across a distance of for example, ten or more meters, including bridges and viaducts. These structures require temporary access from beneath during construction, inspection and maintenance routines, however access can be difficult. One method of access is to build a temporary scaffold from the ground up but this is unfeasible in many circumstances. Another method is to build a walkway or gantry whilst the structure is being built, however this increases costs at that stage, requires foresight and also may require security to prevent unauthorised access of the gantry.
It has therefore been recognised for a long time that a temporary structure, that is cheap and easy to deploy; is adaptable to a variety of different locations and situations; and which is safe and easy to use is wanted for construction, inspection and maintenance.